MDF speaker build

[gychang]

Titebond I, II, or III. I usually use II.

III is darker and more water resistant. I is least strong (but still VERY strong), and not suitable for anyting outdoors (not water resistant). II is a good compromise

I see Titebond II all the time, didn't realize it gets activated with heat, thought it was just a "regular" wood glue. thanks for the tip, now I know how to veneer, now have to find a good place to buy the veneer on the net.

gychang

[BigguyZ]

I use Titebond II, as the original Titebond has a smaller open time and may set too much before you get an even layer on all of the mating surfaces. Another tip regarding the iron-on method for veneering, use painter's tape to mask already applied sides when adding veneer to another face. That way you won't get glue on the surface that you can't remove.

[GaryA]

You guys have me a little more concerned about MDF than I have been in the past. I've got a DC hooked to bt BT3100, using the shark guard with shop vac attached when possible (unless doing dadoes, etc) and using a JDS air filtration ceiling mounted - 11x20 shop, 9 1/2' ceiling. Do I still need a mask or respirator?

[Alex Franke]

I've got a DC hooked to bt BT3100, using the shark guard with shop vac attached when possible (unless doing dadoes, etc) and using a JDS air filtration ceiling mounted - 11x20 shop, 9 1/2' ceiling. Do I still need a mask or respirator?

Just make it a habit.

MDF (and other pressed sheet goods) is usually made with a urea formaldehyde resin, which slowly releases tiny amounts of toxic formaldehyde gas over time, even if it's not being worked. Working it just realeases a lot more in a shorter period of time. That's why it's usually recommended to finish the whole project (including backs, bottoms, insides, etc) to seal in the resin.

In larger amounts, it can irritate the eyes & throat, and cause headaches. If you decide you want to dine on it, it can kill you. (I think the body converts it to fromic acid -- the same stuff you get when you're stung by a bee.) The EPA calls it a "probable human carcinogen".

I did a quick google and came up with this good article from the National Cancer Institute. http://www.cancer.gov/cancertopics/f...k/formaldehyde

All that said, I wouldn't fear it (I use it a lot, too) -- I'd just respect its unique properties and work safely with it, just like saw blades, nails, finishes, and just about everything else you find in the shop. Even some woods are toxic and can cause irritation. Black walnut, for example, contains juglone, with can be an irritant, and can kill tomatoes, peppers, eggplant (and some other plants) if you mulch them with its dust or shavings.

[gychang]

MDF is prone to splitting, also. If you're using screws, always drill pilot holes and try to keep the screws in about an inch from the edge, if possible.

How would I mount the speaker?, would be near the hole, would I need to use the t-nut?

gychang

[gychang]

To make the boxes, I didn't use any fasteners. I simply used butt joints and plenty of Tightbond II glue. I didn't have any issues with the strength of the box at all- I found that they were plenty strong. I like the paper-backed veneer to work with, since it's less likely to crack. To apply, I used the iron on yellow glue method.

how did u mount the speakers?, screw won't hold on MDF, did u use some other fastener?

Thanks, I will try the paper-backed veneer on MDF. (I will wear the mask and cut the mdf out doors).

gychang

[LinuxRandal]

Just make it a habit.

MDF (and other pressed sheet goods) is usually made with a urea formaldehyde resin, which slowly releases tiny amounts of toxic formaldehyde gas over time, even if it's not being worked. Working it just realeases a lot more in a shorter period of time. That's why it's usually recommended to finish the whole project (including backs, bottoms, insides, etc) to seal in the resin.

In larger amounts, it can irritate the eyes & throat, and cause headaches. If you decide you want to dine on it, it can kill you. (I think the body converts it to fromic acid -- the same stuff you get when you're stung by a bee.) The EPA calls it a "probable human carcinogen".

And here I was all this time, thinking I am going to end up with formaldehyde in me anyway

Unless I am cremated

[jziegler]

gychang,

MDF holds screws well enough to hold the drivers in. As long as it's a coarse thread screw, it should be fine. Predrill and screw them in.

Jim

[gimpy]

I'm not real crazy about using t-nuts in mdf. I have one speaker where the t-nut did not pierce the mdf and bent, so it just sits there and spins. I have not taken the speaker out in an attempt to remove/repair that one screw/t-nut. After that, I tried using what is sold as a "hurricane" nut. It has barbs or wings on it and goes in a pre-drilled hole (like the t-nut). It seems to do a better job for me than the t-nuts. I ordered mine through Parts Express, but I'm sure you can find them other places.

I have read where people glue small pieces of plywood on the backside of the mdf where the t-nuts go. The t-nuts sink into the plywood (much better than the harder mdf) and hold pretty good.

Frank

[downtheroad]

In the Oct/99 issue of American Woodworker there was an article by Bob Wayland on making mdf speakers. A Google search came up with this link:
http://www.speakercity.com/Merchant2...y_Code=Article

Hope this helps,
Tony